A Direct-fired gas heating and ventilating unit(s), as indicated on the
drawings shall be furnished. Orientation shall be horizontal (Down) (Side)
discharge. Unit(s) shall be factory assembled, tested and shipped as a complete
packaged assembly, for indoor or outdoor mounting, consisting of the following:

Unit housing shall be constructed of 20 Gauge G-90 galvanized steel.
The wall panels and roof panels shall be fabricated by forming
double-standing, self-locking seams that require no additional support.
The floor and wall panels shall be caulked air tight with a silicone
caulk. All casing panels shall be attached with sheet-metal, screws
or rivets which can be removed to field service large components. The
unit base shall be suitable for curb or flat mount. Housing construction
should be suitable for outdoor or indoor installation.

An observation port shall be located on the exterior of the unit for
observation of the main flame and pilot flame. All controls, gas valves,
modulating controls and electrical components shall be mounted within the,
burner vestibule. The burner vestibule shall be an integral part of the
unit and not extend outside the exterior casing of the unit and not
exposed to the main air stream.

The vestibule full-size door shall provide easy access to controls
and gas-train components. Blower door shall provide easy access to
blower, motor and drives. Access doors shall be provided on both front
an back side of unit providing full access to every part of the unit.

Base

The base shall be constructed of galvanized steel for improved rigidity.
Base shall be structurally reinforced to accommodate the blower assembly
and burner.

Blower

Blower(s) shall be forward-curved, centrifugal, Class I or II,
(depending on requirements of the application) double width,
double inlet, constructed G-90 galvanized steel.
Unit shall have a heavy-duty, solid-steel shaft.
Wheels shall be balanced in two planes and done in accordance
with AMCA standard 204-96, Balance Quality and Vibration
Levels for Fans. The wheel blades shall be aerodynamically
designed to minimize turbulence, increase efficiency and
reduce noise. The wheel blades shall be securely attached
to the wheel inlet ring. The wheel shall be firmly attached
to the fan shaft with set screws and keys. The blower assembly
shall be isolated from the fan structure with vibration isolators.

Shafts shall be precision ground and polished. Heavy duty,
pre-lubricated bearings shall be selected for a minimum (L50)
life in excess of 200,000 hours of operation at maximum cataloged
operating speed. They shall be designed for, and individually tested
specifically for use in air handling applications.

The gas burner shall be a direct-fired, draw-through type, sized to
provide an output of ________ BTU/hr using (natural) (propane) gas
at an inlet-supply pressure to the unit of _____ inches water column
(7" w.c. minimum).

The burner shall be capable of heating the entire air supply
from _____F° to _____F° ( ______ degrees F temperature rise).
The burner shall burn over its entire length at all times when the
system is in operation.

The burner shall have non-clogging, 4302B stainless-steel
combustion baffles attached to a ductile aluminum gas-supply
section with no moving parts to wear out or fail. The burner
shall be capable of 92% combustion efficiency with a maximum
turndown ratio of 15 to 1.

The gas burner shall be, furnished with a pilot package arranged
so that the pilot flame lights the burner with instantaneous
ignition. Pilot assembly includes a flame rod, spark rod and
pilot—automatically ignited by a 6,000 volt ignition transformer.
A flame-rod rectification system shall be used to
prove pilot and main flame.

Rear access doors or a removable lid will provide complete
access to burner and pilot assembly.

Burner profile plates shall be self-adjusting to operate across
the complete CFM range of each model heater. Every unit shall be
design for Variable Air Volume capabilities.

GAS EQUIPMENT

Standard

All gas equipment shall conform to local-Code requirements

Components:

1. pilot-gas shut-off valve

5. main-gas regulator

2. pilot-gas regulator

6. two solenoid valves

3. pilot-gas valve

7. modulating-gas valve

4. main-gas shut-off valve

8. burner

All gas manifold components shall be piped and wired at the factory.

Optional

high-gas pressure regulator

SAFETY CONTROLS

Standard

1. motor starter with adjustable overloads

5. main-gas regulator

2. air-flow safety switch

6. two solenoid valves

3. electronic flame-safety relay

7. modulating-gas valve

4. high-temperature limit switch

8. burner

9. Adjustable burner ON/OFF inlet air ductstat to shut off burner when inlet air is sufficiently warm to maintain space temperature.

Proof-of-closure switch to energize the main-burner circuit only if the motorized gas valve is in a closed position.

ACCESSORIES

Inlet Dampers: Manufacturer shall provide and install on unit,
when possible, a two-position, motor-operated damper with internal end switch
to energize the blower-starter circuit, when damper is 80% open. Blades shall
be a maximum of 6" wide 16 Gauge G-90 galvanized steel shall be made to
guarantee the absence of noticeable vibration at design air velocities.
Damper blades to be mounted on friction-free synthetic bearings. Damper
edges shall have PVC coated polyester fabric mechanically locked into blade
edge. Jamb seals to be flexible metal, compression type.

Filters: The filters shall be (2") thick, aluminum mesh,
coated with super-filter adhesive. Aluminum-mesh filters shall have aluminum
frames with media to be layers of slit and expanded aluminum, varying in pattern
to obtain maximum depth loading. Washable 2" filters shall be enclosed in
two-piece, die-cut frame with diagonal supports. Frame shall be constructed
of heavy-duty beverage board. Filter media is supported on the air leaving
side by a metal grid.

Filter Section: shall be (insulated) (uninsulated) constructed of G-90
galvanized steel with filter supported by internal slides and with removable access panels.
Filters shall be provided in a filtered intake.

Maxitrol Series 14: For building exhaust-air
replacement to maintain a constant discharge temperature of supply
air. The burner flame modulates to compensate for outdoor
temperatures. The optional manual SUMMER-OFF/WINTER selector
switch and exhaust system interlock control the heater-blower
operation. Supplied with optional remote-control panel with
temperature selector dial and SUMMER-OFF/WINTER selector.

A single point electrical connection shall be supplied. The control
circuit voltage shall be 115 volts. A control transformer shall be
provided, when required. The control wiring shall be carried in wire
channel or conduit. Wiring in control enclosures shall be in
accordance with the National Electrical Code and the local code, as
it may affect the installation. Motor starter shall be provided.
Starter shall be line voltage, definite purpose type.

Unit(s) shall be complete with all items such as relays, starters,
switches, safety controls, conduit and wire as previously mentioned,
and as required for proper operation. All factory-mounted controls
shall be factory prewired to the unit control panel.

FACTORY TESTED

Unit(s) shall be operated, tested and set at the factory using job-site
conditions for electrical and gas input. All operating and safety controls
shall be tested and set at the factory. Adjustable, or fixed sheaves shall
be set for proper RPM at specified conditions. Gas-pressure regulator shall
be set for specified burning rate at specified inlet pressure.

SERVICE AND PARTS

The supplier shall furnish gas piping schematics, as built
wiring connection and control-circuit diagrams, dimension
sheets and a full description of the unit(s). Service manuals,
showing service and maintenance requirements, shall be provided
with each unit.